The TelegraphITV's 'Endeavour' imagines the early years of Oxford sleuth Inspector Morse. Olly Grant meets its star.

Liverpool-born actor Shaun Evans was under no illusion of the daunting task he faced stepping into the shoes of the late John Thaw. Last August, 31-year-old Evans was unveiled as the face of ITV’s Inspector Morse prequel, Endeavour – the title referring to Morse’s long-hidden Christian name – which airs on Monday, marking the 25th anniversary of the original series.

Set in 1965, it sees Colin Dexter’s beloved sleuth transformed into a younger version of the Morse we knew from 1987 until 2000. A rookie cop. A teetotaller. A proto-Morse. And a disillusioned one, on the brink of resigning from the force. “You find him at a point where he’s like, ‘I don’t know if I can do this any more,’ ” says Evans. Until, that is, a murder case sets him on the road to, well, everything that follows.

News of the prequel catapulted Evans from rising star (best known for gangster drama The Take) to object of mainstream scrutiny. Fan reaction, though, was mostly disapproving – not of Evans so much as the toying with Morse’s legacy. “IS NOTHING SACRED???” read a typical tweet. Evans didn’t go online to read them. “That’s not my bag,” he says. But anyway, he adds, why be cowed? “You just have to get on with it.”

Seated in his on-set caravan, Evans shows me his character’s jacket, bought from a period clothes shop in London’s Ladbroke Grove. “It’s an original 1960s Burton suit,” he says proudly. “It took me five hours to find,” which says something about his eye for detail. A singular dedication to a correct outcome. Now, who does that remind you of?

Morse fans can take comfort in the knowledge that Dexter had a hand in Endeavour. Following a short story he wrote for a newspaper in 2008, Dexter was asked to consider a TV version. Dexter said yes. And though he didn’t pen the script (that fell to Russell Lewis, who had previously written episodes of both Morse and its spin-off Lewis), he did approve Evans’s casting, and also wangled his trademark cameo.

In fact the film is rammed with intertextual nods and winks. We meet The Car: a black Mark 1 Jag rather than the burgundy Mark 2. And we watch Endeavour Morse have his first beer, solve crosswords and recoil at corpses – Morse being famously squeamish. The Morse-Lewis coupling is also reworked, with Endeavour playing understudy to DI Fred Thursday (The Thick of It’s Roger Allam). There’s even a reference to Thaw himself (who died in 2002) via his actor daughter, Abigail, who plays a journalist.

Evans hopes all the references won’t be seen as de trop. “You have to pay attention to those things because you want to please the audience,” he explains. “But you have to want to do your own thing with it as well.” Did he ask Dexter for pointers? “Not really.” He thinks for a second. “It’s like any job. You don’t want someone telling you how to do it. I need to find out for myself.” Pause. “I’m not being overconfident. But if I was to go cap-in-hand to everyone who had an opinion, I’m not paying attention to my own.” While he devoured old episodes, he was determined not to simply replicate Thaw: “I certainly wasn’t copying any walks, talks or tics.”

One thing Evans did borrow from Thaw, though, was his intensity. Allam, who once appeared in a 1997 episode of Morse, thinks this was one of Thaw’s gifts. “There was always the sense of a rich interior thought process,” he says, and he thinks Evans captures this too.

Has Evans absorbed Morse’s pedantic qualities? I ask it jokingly, but Evans considers carefully. “He’s a big thinker, and I’ve been thinking about things more,” he says. “You end up taking on a predominant atmosphere of whatever that person is like.” For example, he says, three years ago he played Kurt Cobain in the play, Kurt and Sid. “It was only afterwards that I thought, God, I’ve gone absolutely mad.”

The question is: will viewers now see Morse through the prism of Evans? ITV certainly hope so, since the concept would translate naturally to a series. But Evans thinks Endeavour can stand alone. “Listen, I hope previous generations enjoy it as much as the original. But my hope is that we get a new generation of people who enjoy this one film, too.”